<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script type="text/javascript">
        let arr = [1,3,5,7,9]
        let arr2 = arr.map((item,index)=>{
            return item+'ss'
        })
        // map加工数组，但不影响原数组
        console.log(arr2);
    </script>
</body>
</html>